Upgrade Kafka Streams Benchmarks to Kafka Streams 3.1

Fix #303 (closed). Depends on !226 (merged)

theodolite-benchmarks/load-generator-commons/src/test/java/theodolite/commons/workloadgeneration/HttpRecordSenderTest.java

@@ -45,8 +45,9 @@ public class HttpRecordSenderTest {
     final ActivePowerRecord record = new ActivePowerRecord("my-id", 12345L, 12.34);
     this.httpRecordSender.send(record);
 
+    final String expectedJson = "{\"identifier\":\"my-id\",\"timestamp\":12345,\"valueInW\":12.34}";
     verify(exactly(1), postRequestedFor(urlEqualTo("/"))
-        .withRequestBody(equalTo(this.gson.toJson(record)))); // toJson
+        .withRequestBody(equalTo(expectedJson))); // toJson
   }
 
 }